There is concern over short- and long-term environmental and socioeconomic effects of large-scale biofuel production. These concerns relate to the energy balance of biofuel production, conversion, and use; soil and water quality effects; poor resilience of monocultural plantations; and the implications of biofuels for biodiversity, sustainability, and amenity (Cook et al., 1991; National Audubon Society, 1991; Brown, 1998; Christian et al., 1998).
Large-scale bioenergy plantations that generate high yields with production systems that resemble intensive agriculture would have adverse impacts in place of natural forest. With the development of conversion technologies that are efficient at small scales, however (Bowman and Lane; 1999; Larson and Jin, 1999; Prabhu and Tiangco, 1999), transportation costs are reduced and large monocultures are unnecessary (see Fact Sheet 4.21). Small-scale plantations on degraded land or abandoned agricultural sites would have environmental benefits. The key is to consider site-specific circumstances rather than make generalizations.
Significant amounts of fossil fuels are used in the production, harvest, and transport of biofuels; the net carbon benefit of biofuels must account for this fossil fuel use. Energy input-output ratios in biofuel production are 1:10 to 1:15 and improve to 1:30 (Turhollow and Perlack, 1991). As with fossil fuels, overall system efficiency is lower because of the characteristics of conversion processes (e.g., Graham et al., 1992; Matthews et al., 1994; Boman, 1996; Mann and Spath, 1997).
Biodiversity concerns relate to plantation species and plantation habitat conditions. Plantations with only a small number of species achieve the highest yields and the greatest efficiency in management and harvest, but good plantation design now includes set-asides for native flora and fauna and blocks with different clones and/or species. The variety of species in biofuel plantations falls between that for natural forests and annual row crops. Research on multi-species plantations and management strategies and thoughtful land-use planning to protect reserves, natural forest patches, and migration corridors can help address these issues.
Concerns regarding food supply and access to land for host communities are addressed through community-scaled plantations that feed small-scale conversion technologies, meet local fuel and timber needs, provide employment with biofuel-powered rural electrification, and export liquid fuel products (Read, 1999; Fact Sheet 4.21). Higher incomes may enable communities to invest in modern food production and replace traditional agriculture, which appears unsustainable with predicted population and climate change. A barrier to community-scaled biofuel systems is a lack of institutional and human capital to ensure biofuel projects that meet local needs rather than foreign investors' carbon credit priorities.
Other reports in this collection